Population outbreaks of crown-of-thorns seastars (CoTS; Acanthaster spp.) are contributing to extensive coral loss and reef degradation throughout the Indo west-Pacific, but the causes and underlying mechanisms of population maintenance and outbreaks are equivocal. Two recent publications suggest that, in addition to outbreeding sexual reproduction, asexual reproduction through larval fission and selfing may contribute to rapid increases in the local abundance of Acanthaster spp. We re-analysed two large microsatellite datasets (collectively representing 3,714 individuals) that investigated connectivity in the Great Barrier Reef and Pacific region to investigate if potential cloning or selfing can be evidenced in the population genetic structure. Within this dataset we identified only a small number (18, < 0.5%) of putative clones (repeated multi locus genotypes). We argue that several of these are due to sampling and processing errors rather than direct evidence of cloning. Analysis of the population genetic structure (i.e., pairwise genetic differences between individuals, deviations from Hardy-Weinberg-Equilibrium, and linkage disequilibrium) also yielded no genetic evidence for asexual reproduction. There was a tendency towards slight heterozygote deficits, so we cannot refute that selfing does occur, but this is mostly likely attributable to sampling artefacts. Although we cannot exclude that asexual reproduction occurs to some extent in Acanthaster populations, we find no evidence that these processes make a contribution to population structure or directly enhance larval supply.

data are microsatellite data in genalex format. Originally published in 2 previous publications, populations are differently grouped (as described in the new population):

Yasuda N, Nagai S, Hamaguchi M, Okaji K, Gerard K, Nadaoka K (2009) Gene flow of Acanthaster planci (L.) in relation to ocean currents revealed by microsatellite analysis. Molecular Ecology 18:1574-1590

Harrison H, Pratchett M, Messmer V, Saenz-Agudelo P, Berumen M (2017) Microsatellites reveal genetic homogeneity among outbreak populations of Crown-of-Thorns Starfish (Acanthaster cf. solaris) on Australia’s Great Barrier Reef. Diversity 9:16